docs: def return_port(port):
      """Return a port that is no longer being used so it can be reused."""
      if port in _random_ports:
          _random_ports.remove(port)
      elif port in _owned_ports:
          _owned_ports.remove(port)
          _free_ports.add(port)
      elif port in _free_ports:
          logging.info("Returning a port that was already returned: %s", port)
      else:
          logging.info("Returning a port that wasn't given by portpicker: %s",
                       port)